The James Webb Space Telescope (JWST) has detected a carbon molecule thought to be a cornerstone of interstellar chemistry in a planet-forming disk of gas and dust around a young star, a recent study reports.
JWST found the carbon compound methyl cation (CH3+) in a protoplanetary disk system called d203-506, which is about 1,350 light-years from Earth in the Orion Nebula. The star at the center of the system is a red elf It’s only 10% the size of our sun, and the entire system is bombarded with powerful ultraviolet radiation from nearby hot, young, massive stars.
Scientists say that most protoplanetary disks are subject to intense ultraviolet radiation at certain times, because stars tend to form in groups that include massive, ultraviolet-producing ones. stars. This includes our own cosmic neighborhood; evidence from meteorites indicates that our baby solar system was subject to an intense bombardment of such radiation that formed about 4.5 billion years ago.
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Such intense radiation bombardment must destroy the complex organic molecules needed to form the basis of life. But we know that this is not always the case; life exists in land, after all. The discovery of methyl cations in a region where planets are forming that could eventually host life could help solve this cosmic riddle and help scientists better understand how and where in the universe life originated. can start.
Despite being a relatively simple molecule, the methyl cation has been at the center of theories of cosmic carbon chemistry since the 1970s due to the fact that, like other carbon-containing ions (molecules with an electrical charge), it is easy it reacts with a wide range of other molecules. This means it can start growing more complex carbon molecules, even at low temperatures.
Carbon chemistry like this is of particular interest to astrobiologists, because life as we know it is based on carbon. However, until JWST took off, astronomers were unable to detect this carbon molecule in relatively distant planet-forming disks.
This is because observing protoplanetary disks with radio telescopes requires molecules that have a so-called “permanent dipole moment,” meaning they have a positive and a negative “end.” The methyl cation has no permanent dipole moment. And ground-based optical telescopes experience too much atmospheric interference to detect it from the light it absorbs and emits, a process called spectroscopy. That means that detecting the methyl cation requires a very sensitive space telescope like JWST, which began operating in the summer of 2022.
“This detection of CH3 + not only proves the incredible sensitivity of JWST but also confirms the postulated central importance of CH3 + in interstellar chemistry,” said study team member Marie- Aline Martin, a researcher at Paris-Saclay University, said in a statement.
As for the puzzle of how organic molecules can survive a burst of ultraviolet radiation, Martin and colleagues think they may have a solution. The team suggests that the methyl cation may actually appear at such locations directly as a result of ultraviolet radiation providing the energy needed to form the molecule.
There are other signs that the bombardment of ultraviolet radiation may also affect protoplanetary disks. For example, JWST observations suggest that less illuminated disks have more water than those, such as d203–506, where the team found no water.
“This clearly shows that ultraviolet radiation can completely change the chemistry of a protoplanetary disk,” study lead author and University of Toulouse scientist Olivier Berné said in the same statement. “It may have actually played a critical role in the early chemical stages of the origin of life by helping to make the methyl cation – something that was probably underestimated before.”
The research was published in April in Letters in the Astrophysical Journal.
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